Method and apparatus for folding a carton blank

ABSTRACT

An apparatus and method for folding a planar box blank having a plurality of panels defined by fold lines wherein the blank is continuously moved along a predetermined path by conveyor means, certain of the panels of said blank being held in controlled contact with said conveyor means, and others of said panels being subjected to a plurality of air jets continuously issuing from an air folding rail to cause said last mentioned panels to be folded back into face-to-face relation with those panels in contact with the conveyor means. As the blank moves through the apparatus, a guide rod initiates folding of the blank along the fold lines. As the blank continues on its predetermined path through the apparatus, air jets issuing from the air folding rail continue and complete the folding operation.

United States Patent [191 Randle [111 3,797,371 1 Mar. 19, 1974 METHOD AND APPARATUS FOR FOLDING A CARTON BLANK [75] Inventor: Fred W. Randle, Modesto, Calif.

[73] Assignee: International Paper Company, New York, NY. p

22] Filed: Deer 29, 197.1 21 Appl. No.: 213,586

[52] US. Cl. 93/52, 93/39 R, 93/41 [51] int. Cl. ..B3lb 1/42, B3lb 1/72 [58] Field of Search 93/52, 41, 39 R, 48, 53 SD,

93/53 R, 49 M, 49 R [56] I References Cited UNITED STATES PATENTS 2,783,693 3/1957 Felber 93/52 3,110,232 11/1963 Frei 93/49 R 3,122,069 2/1964 Lopez... 93/52 3.572.221 3/1971 Baum.... 93/52 3.605.585 9/1971 Borders 93/52 AZ 42 ,,I 4 -l-.. 7 g i i I 20 Primary Examiner-Andrew R. Juhasz Assistant Examiner-Horace M. Culver Attorney, Agent, or Firm-Ronald F. Ball [5 7 ABSTRACT An apparatus and method for folding a planar box blank having a plurality of panels defined by fold lines wherein the blank is continuously moved along a predetermined path by conveyor means, certain of the panels of said blank being held in controlled contact with said conveyor means, and others of said panels being subjected to a plurality of air jets continuously issuing from an air folding rail to cause said last mentioned panels to be folded back into face-to-face relation with those panels in contact with the conveyor means. As the blank moves through the apparatus, a guide rod initiates folding of the blank along the fold lines. As the blank continues on its predetermined path through the apparatus, air jets issuing from the air folding, rail continue and complete the folding operation.

1 Claim, 9 :Drawing Figures PMENTEDMAR 19 I974 SHEET 1 0F 3 PMENTEBMAR as can SHEET 2 BF 3- MN m NQE

PEP N METHOD AND APPARATUS FOR FOLDING A CARTON BLANK BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to folding a blank into a collapsed or knocked down" carton. It involves the use of a conveyor device to carry the blank on a predetermined path into and through a folding station, means for controlling the blank and maintaining portions thereof in contact with the conveyor as the blank passes through the folding station,- and an airfolding rail disposed along the path of the blank for continuously .directing a plurality of air jets against other .selected portions of the blank. gradually to guide the said selected portions of the blank into face-to-face relation with those portions of the blank held in contact with the conveyor.

2. Description of the Prior Art Various prior art devices utilizing intermittent jets of compressed air to fold the flaps of a moving cardboard blank to form a box are shown in U.S.- patent to Frei No. 3,110,232. US. patent to Vergobbi No. 2,533,642 shows the use of an air jet to maintain a flap or tab previously'loosely folded by mechanical means in a desired position. The use of air jets to tuck the corners of a thin metal foil blank against a die block is disclosed in US. patent to Daniel] No. 1,908,823. In addition, a web folding apparatus in which a layer of gas delivered from a perforated tubing serves to maintain the web separated from the folding apparatus while the web is being continuously advanced and folded upon itself is described in [1.5. patent to Ramaika No. 3,191,926. The same principle applied to the formation of a tube of plastic film in which the film is drawn over the upper edge of a mandrehbut separated therefrom by a cushion of air, is shown in U.S. patent to Vichos No. 3,370,517. U.S.patent to Boughton No. 2,605,195 discloses the use of blasts of air to progressively turn a fabric band over a bead wire in the manufacture of a tire.

However, in none of thesedevices is there disclosed an apparatus or method for folding a continuously moving cardboard box blank bythe use of aplurality of continuous jets of compressed gas, and in which adequate control of the blank during the folding operation is possible.

Difficulties have been encountered inusing various prior art devices for folding blanks into cartons'For example, control of the blank during folding and proper registration thereof on high speed machinery have been problems. When control of the blank is inadequate, false creasing of the panel, i.e., folding other than at the prescored fold lines, may occur, producing rough, uneven and unusable cartons. In addition, it is frequently the practice to print a carton blank at a station immediately prior to folding the blank from its initial planar form. Such printing and folding operations are often done on the same continuous, high speed production line. Where this practice is followed, little time is available to allow the printing ink to dry before the blank passes into the folding station. Where mechanical folding devices, such as blades or arms or other abutting surfaces, with which the printed portions of the blank may come in contact, are used in order to carry out the folding operation, they are likely, because of the sired conformations.

SUMMARY OF THE INVENTION 1 have found that the use of my folding apparatus overcomes the difficulties attendant upon using the conventional mechanical folding devices.

One general object of this invention, therefore, is to provide a new and improved apparatus and method for folding a continuously moving prescored box blank.

More specifically, it is the object of this invention to provide an apparatus and method which maintains controlof the box blank during folding action.

Anotherobject of this invention is to provide an apparatus and method in which folding of a box blank into the form of a collapsed carton is effected by subjecting portions of the blank to a plurality of continuous jets of compressed air.

Still another object of the invention is to provide a novel apparatus and method to eliminate false creasing of the panel during folding and to thereby producea more even and smoother box. I

A further object of the invention is to provide an apparatus and method for folding a prescored box blank which will eliminate smearing of freshly printed box blanks as they pass through the folding station. The novel apparatus and method of my invention will also permit the use of heavier and greater quantities of ink in printing carton blanks immediately prior to the folding station. In addition, the use of a plurality ofcontinuous jets of compressed air to fold the freshly printed blanks will decrease the time ordinarily required to dry the ink, thus reducing the likelihood of accidentally smearing the ink through handling subsequent to the folding operation. V t

In oneiillu'strated embodiment of this invention there is provided amachine and method for automatically folding a prescored box blank at high production speeds. The machine embodying the present invention is particularly suited for high speed folding of prescored printed blanks wherein the blanks are printed immediately prior to entering the folding station and theprinting ink on the blanks has not had sufficient time to dry before being subjected to the folding operation. The blank is moved continuously through the apparatus on a conveyor belt having associated therewith means for maintaining control of the blank as it'passes into and through the folding station. These control means comprise a series of hold-down rollers followed by an elongated spring steel hold-down strip disposed above the conveyor belt together with a vacuum device in the form of suction boxes disposed beneath the conveyor belt. v

If desired, the means for maintaining control of the blank as it passes out of the bite of the hold-down rollers and into and through the folding station may be limited solely to the action of one or more spring steel hold-down strips, or, in the alternative, solely to the action of thevacuum device. In other words, either or both of these, devicesmay be used to maintain control of the blank. In my preferred embodiment, as described i more fully hereinafter, I have used both devices.

The folding station includes a pair of mechanical guide rods for initiating the folding action and a pair of air folding rails to continue and complete the folding of the blank into the form of a collapsed carton. The prescored blank is presented to the folding station in planar form. One of the mechanical guide rods contacts the leading edge of each of the particular panels of the blank to be folded and initiates upward movement thereof relative to the immediately adjacent panel which is held in contact with the conveyor belt. Each air folding rail is formed from a length of tubing connected to a source of air under pressure. The tubing has a plurality of apertures disposed at predetermined radial locations relative to the axis thereof along the length of the tube. The air folding rail extends generally parallel to the path of the blank as it passes through the apparatus. These apertures are positioned in a manner such that continuous jets of compressed air issue therefrom, each of the successive jets being positioned relative to each other and to a blank passing through the apparatus so that the air jets strike the surface of the panel that has been subjected to the initial folding action of the mechanical guide and completes the fold by bringing thatpanel into face-to-face engagement with that portion of the blank being .held in engagement with the conveyor.

I If desired, the entire folding operation, including initiation thereof, may be carried out by the use of air jets striking against the surface or surfaces to be folded. In other words, air jets from either the air folding rail or a separate jet device could'be substituted for the mechanical'guide rod to initiate folding of the blank.

It will be understood, as shown in the preferred embodiment of my invention, that a pair of mechanical guide rods followed by a pair of air folding rails are utilized in order to effect substantially simultaneous folding of two panels of the blank as it passes through the machine. i

The apparatus illustrated is designed particularly for folding a prescored, precut and preprinted blank into a carton in its knocked down or collapsed form. It will be understood that the blank as fed to the folding machine of the present invention will have been impressed with score or fold lines and will have been properly cut at predetermined locations so that eventually it may be set up as a carton. One face of the carton blank will have been printed with the desired legend. In addition, an adhesive will have been applied to one face of a glue tab located at one end of the carton blank. Normally these operations are completed in-the sameproduction line as, andimmediately prior to, the folding operation.-

The product issuing from the apparatus is essentially a collapsed rectangularly shaped tube open at both ends which may in subsequent operations be erected simply and economically by exerting light pressure on opposing edges of the collapsed tube. The precut and prescored ends may then be folded to form the top and bottom panels of an erected carton.

The present invention, as well as further objects and features thereof, will be understood more clearly and fully from the following description when read with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS F IG; 1 is a plan view of the apparatus of my invention with portions broken away and showing a carton blank in dashed lines at several progressive stages as the blank passes from left to right through the apparatus.

FIG. 2 through FIG. 5 are vertical cross-sectional views of the apparatus of FIG. 1, taken generally along the lines 2-2, 3-3, 4 -4 and 5-5, respectively, of

DESCRIPTION OF THE PREFERRED EMBODIMENT The apparatus of my invention comprises essentially a pair of driven endless conveyor belts 10 and 11, each of which is supported by a plurality of idler rolls 12, a pair of guide rods 13 and 14, 'a pair of spring steel holddown strips 15 and 16, a pair of vacuum boxes 17 and 18, and a pair of air folding rails 19 and 20. It may be observed from the drawings that each of the conveyor belts, guide rods, hold-down strips and vacuum boxes are essentially identical, one of each pair being disposed on one-half of the machine along its longitudinal axis, as clearly shown in FIG. 1. Where one of these devices is described in detail, it should be understood that the description is equally applicable to either of the devices of each pair. While the air folding rails are generally similar, there are significant differences in location and structure which will be described.

The conveyor belts l0 and 11 are made of a flexible material such as rubber, plastic or the like, and the outer face thereof may be corrugated as at 9. Each of the conveyor belts is driven-by driven roller or pulley 21 connected to motor M. The tension on each conveyor belt may be adjusted by conventional tensioning means 22. On its upper reach the conveyor belt travels over a plurality, of idler rolls 12. Positioned above the upper reach of the conveyor belt are a series of holddown rolls 23 on the entrance end of the machine (to the left in FIGS. 1 and 6) and hold-down rolls 24 on the exit end of the apparatus (to the right in FIGS. 1 and 6), the purpose of which will be described more fully hereinafter.

A pair of guide rods 13 and 14 are positioned atthe entrance end of the machine. Referring to guide rod 13, as is shown in FIGS. 1, 2 and 3, its front end 25 is positioned on a level with the upper reach of conveyor belt 10 and spaced laterally therefrom (see FIG. 3 in which. the guide rods 13 and 14 are shown although, in fact, they are positioned to the left of line 3-3 of FIG. 1 Guide rod 13 is inclined upwardly from its front end 25 toward the exit end of the apparatus and, in addition, converges from itsfront end 25 toward the longitudinal axis of the apparatus. Guide rod 13 is bent at 26 and fastened at 27 to frame 28. Similarly, the front end 29 of guide rod 14 (FIGS. 1-3 and 6) is positioned on a level with the upper reach of conveyor belt 1 1. Guide rod 14 is inclined upwardly from its front end 29 toward the exit end of the apparatus and also converges from its front end toward the longitudinal axis of the apparatus. It is bent at 30 and fastened at 31 to frame 28.

Spring steel hold-down strip 16 is mounted adjustably at one end in block 32 and extends outwardly along and in contact with the corrugated surface 9 of conveyor belt 11. Spring steel hold-down strip is similarly mounted at block 33 so that it extends outwardly along and in contact with conveyor belt 10.

An elongated vacuum or suction box 18 of rectangular cross section is located adjacent, but slightly below and parallel to, a portion of the upper reach of com veyor belt 11. The vacuum box is connected at 34 to conduit 35, which in turn is connected to a vacuum pump 36 driven by motor 37. Similarly, vacuum box 17 is connected at 38 to conduit 39, which in turn is also connected to vacuum pump 36. The top of each of vacuum boxes 17 and 18 is equipped with an open grid-like cover 40. Cover 40 supports perforated endless belt 41 (shown partly broken away in FIG. 1) of polyethylene or other flexible material which is mounted for continuous longitudinal movement with respect to the grid like cover. Belt 41 is driven by driven roller or pulley 21 connected to motor M. Belt 41, as conveyor belts 10 and 1 1, may be tensioned by means of the conventional tensioning device 22. It will be understood that there is a separate perforated belt 41 for each of the vacuum boxes 17 and 18. When a vacuum is applied to the suction boxes through conduits 35 and 39 connected to vacuum pump 36, air is drawn 'into each of the vacuum boxes through perforated belt 41. As shown in FIGS. 2 through 5, perforated belts 41 run substantially parallel to and on the same level as conveyor belts l0 and 11.

A pair of air folding rails 19 and extend generally parallel to the longitudinal axis of the apparatus. Each of these air folding rails, which in my preferred embodiment are made of five-eights inch OD seamless steel tubing, is positioned for its full length above the upper reach of the conveyorbelts 10, 1 1.

The front end 420f air folding rail 20 is located laterally outwardly of .a verticalplane drawn through conwhere the perforations at the end 43 of the tubing are 42 of the rail and progress in a clockwise direction,

ending in the vertical direction at: end 43 of rail 20.

When compressed air is introduced into air folding rail 20 it discharges through the apertures 47 to deliver a plurality of continuous jets of compressed air. Air

folding rail 19 is essentially the same in structure as air.

folding rail 20. The front end 48 of air folding rail 19 is located laterally outwardly of a vertical plane drawn through conveyor belt 10. The other end 49 of the rail 19 is located laterally inwardly of a vertical plane veyor belt 1l.-The other end 43 of the air folding rail is located laterallyinwardly of a vertical plane drawn through conveyor. belt 11, and as shown in FIGS. 1 and 5, extends almost to the longitudinal axis of the apparatus. The front end 42 of air folding rail 20. is connected to a source of air under pressure (not shown). Theend 43 is closed.

In addition to converging from its front end toward the longitudinal axis of the apparatus, air folding rail 20 is inclined downwardly from its front end 42 toward its other end 43. Air folding rail 20 is supported intermediate its ends 42 and 43 by bracket 44 and at a point near its end 43 by adjustable bracket 45. The end 43 of rail 20 may be moved inwardly or outwardly by adjusting a mechanism such as turnbuckle 46.

Air folding rail 20 is provided with a plurality of apertures or perforations 47 between its ends42 and 43. In my. preferred embodiment these apertures are three sixty-fourths inch diameter drilled holes on one-half inchcenters and follow a spiral path through 90 along the longitudinal axis of the air folding rail. The perforations or apertures47 start at the entrance end 42 of rail 20 at a position 90 from a vertical plane drawn through the axis of the tubing. Thisis shown in FIG. 7. Asthe perforationscontinue along the length of the tubing they. progress. radially downwardly to, a point drawn through conveyor belt 10, and extends almost to the longitudinal axis of the apparatus. The perforations in air folding rail 19 extend in a counter-clockwise spiral through along the length of the rail starting in a horizontal direction toward the longitudinal axis of the apparatus at end 48 and progressing to a vertically downward direction at end 49. Folding rail '19 is supported by bracket 50 and adjustable bracket 51. As shown in FIG. Lends 48 and 49 of rail 19 are positioned closer to the exit end of the apparatus than the ends 42 and 43, respectively, of air folding rail 20. It will be appreciated that the relative positions of air folding rails 19 and 20 will result in jets of air issuing from air folding rail 20 at points closer to the front end of the apparatus than jets issuing from corresponding apertures along the length of air folding rail 19.

OPERATION OF THE APPARATUS The apparatus of my inventionv is especially adapted for folding a rectangular box blank having a minimum of four panel sections separated by transverse score lines into theform of a collapsed carton. These score or folding lines are impressed into the blank at a station in advance of my folding apparatus. In addition, the blank may be precut to provide end flaps which will serve as the top and bottom portions of a carton. The prescored and precut blank may also be printed at a station immediately in advance of the described folding apparatus. A blank particularly suited for use in the apparatus of the invention also has a glue tab extending from one end thereof. This glue tab will be given a coating of adhesive immediately prior to passing through the folding apparatus and will serve to permanently join the folded over panels of the blank, as more fully described below.

In FIGS. 1 through 6 there are shown in dash line form four box blanks A, through A These may be considered as either the same blank at four different stages in its passage through the apparatus, or four separate, but identical, blanks being continuously fed through the machine at high production speeds. The four blanks A, through A, are illustrated to show the man ner in which a blank is progressively folded in its continuous passage through the folding apparatus.

Referring to FIG. 1, a rectangular box blank A. of sheet material is shown separated by transverse score lines 52, 53 and 54 into four panels 55, 56, 57 and 58. The blank also has longitudinal score lines 59 and 60,

as well as cuts 61, 62 at the opposite ends of score line 52, cuts 63, 64 at the ends of score line 53 and cuts 65, 66 at the ends of score line 54. A glue flap 75 extends outwardly from panel 55 between longitudinal score lines 59 and 60. The longitudinal score lines 59 and 60,

as well as cuts 61 through 66 are not utilized in the air folding operation of my invention. They are illustrated here because such score lines and cuts are normally made in advance of any folding operation, and the blank folded by my apparatus normally contains such score lines and cuts. These score lines and cuts serve to define those portions of the blank which will eventually become the top and bottom panels of a carton erected from the collapsed and folded carton issuing from my apparatus.

In operation carton blank A, is delivered to the apparatus of my invention from the front end of my machine (shown to the left in FIGS. 1 and 6) by conveyor belts l and 11 and entrance hold-down rolls 23. The score lines are in the upper face of the blank. A typical blank may be made of paperboard having a corrugated core with facing sheets adhesively secured to opposite faces thereof. In my preferred operation the corrugated paperboard is fed through the apparatus with its fluted edges transverse to the direction of travel of the blank. The prescored and precut panel has freshly printed matter on its bottom face, i.e., the face in contact with the conveyor belts 10 and l 1. In addition, glue has been applied to the underside of glue flap 75.

As the blank A, is moved into the apparatus in a direction parallel to the transverse score lines 52, 53 and 54, hold-down rolls 23 hold the centralor two innermost panels 56 and 57 of the blank in contact with conveyor belts 11 and 10, respectively. Transverse score lines 52 and 54 are outside of the bite of the hold-down rolls 23 and conveyor belts wand 11. As the blank progresses into the apparatus, the leading edge 76 of outermost panel 58 and the leading edge 77 of outermost panel 55 come in contact with and ride up upon guide rods 13 and 14, respectively. As the blank A, progresses further into the apparatus, the contact between the leading edge of outermost panels 58 and 55 and the guide rods initiates upward movementof these two outermost panels along the score lines 54 and 52, respectively. FIG. 2 shows the blank in its planar form as it enters the apparatus. FIG. 3 shows the blank with its two outermost panels 55 and 58 in substantially vertical position, after those portions of the blank A, have been subjected to the action of the guide rods.

It will be noted that a panel A, moves into the machine, the two central or innermost panels 56 and 57 move out of the bite of hold-down rolls 23 and conveyor belts 10 and 11 and move into the area of the vacuum boxes 17 and 18. The bottom face of each of the two innermost panels 56 and 57 is in contact with the perforated endless belt 41 supported by and in continuous longitudinal movement with respect to the open grid-like cover of the suction boxes 17 and 18. With the vacuum turned on the two innermost panels 56 and 57- of the blank will be exposed to vacuum ac-' tion during a portion of the travel of the blank through the apparatus and will continue to be held in contact with the corrugated surface 9 of conveyor belts 10 and 1 l.

As the blank A, continues through the apparatus it passes beneath spring steel hold-down strips 15 and 16 which are disposed directlyabove the conveyor belts l0 and 11 and extend parallel to the direction of movement of the blank. These strips hold the two central or innermost panels 56 and 57 in contact with the conveyor means during a portion of the blanks travel through the apparatus.

As the two outermost panels 55, 58 are folded upwardly along score lines 52 and 54, respectively, by guide rods 14 and 13, respectively, to the position shown in FIG. 3, they are contacted by a plurality of continuous jets of compressed gas issuing from the air folding rails 20 and 19, respectively. Subjecting these outermost panels of the blank to the jets of compressed gas as the blank continues through the apparatus guides the panels into a folded position in which they are in face-to-face relation with the central or innermost panels 56 and 57, respectively. Because air folding rail 20 is positioned closer to the front end of the apparatus than air folding rail 19, as previously described, outermost panel 55 will be subjected to the action of the compressed air issuing from air folding rail 20 sooner than outermost panel 58 is subjected to the action of the air jets issuing from air folding rail 19. The relative position of air folding rail 20 with respect to air folding rail 19 will cause completion of the folding of outermost panel 55 before the completion of outermost panel 58. This is clearly shown in FIGS. 4 and 5. Because glue tab is attached to end panel 55, it will lie beneath a portion of panel 58 when folding is completed, and the adhesive on glue tab 75 will result in a permanent bond between the glue tab and panel 58.

As the blank continues its movement through the apparatus it first passes out of contact with spring steel hold-down strips 15 and 16, but will still be under the influence of the vacuum boxes 17 and 18. It will also be subjected to the force of the downwardly directed jets ofcompressed gas issuing from the air folding rail near the exit end of the apparatus. Removal of the blank from contact with the spring steel hold-down strips permits the outermost panels of the blank to come into face-to-face engagement with the central portion of the blank. v I

As folding is completed the blank comes into the bite of hold-down rolls 24 and conveyor belts l0 and l l on the exit end of the machine. Blank A in its completely folded but knocked down or collapsed form is shown in FIG. 5 and to the right of FIGS. 1 and 6.

Adjustment may be made in the position of air folding rails 19 and 20 to accommodate blanks of different sizes by means of adjustable brackets 51 and 45, respectively,at the exit end of the apparatus.

In operation I have found that air pressures of up to pounds per square inch, measured just upstream of the perforations at the entrance end of air folding rails 19 and 20, may be used. V

The terms and expressions which I have employed are used as terms of description and not of limitation, and I have no intention in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.

I claim:

1. Apparatus for folding a planar blank having a plurality of transverse score lines impressed therein into a collapsed carton by means of a plurality of jets of compressed air applied against portions of said blank which comprises: I

posed adjacent and parallel to the said moving means, each of said suction boxes having an open grid-like cover and a perforated endless belt partially supported by said cover and mounted for continuous longitudinal movement with respect to said cover,

a pair of air folding rails positioned along the path of said moving blank,' each of said air folding rails being formed from tubing and connected to a source of compressed air,

a plurality of perforations in each of said air folding rails extending along the length thereof and positioned at predetermined radial positions with respect to the longitudinal axis of said rail and arrangedfto deliver a plurality of jets of compressed air continuously against the blank as it is moved through said apparatus whereby outer portions of said blank along said transverse score lines are brought into face-to-face engagement with the central portion of the blank,

said jets of compressed air having sufficient force to prevent contact of the blank with said air folding rail during said folding. 

1. Apparatus for folding a planar blank having a plurality of transverse score lines impressed therein into a collapsed carton by means of a plurality of jets of compressed air applied against portions of said blank which comprises: means for continuously moving the blank along a predetermined path parallel to the direction of said transverse score lines, a vacuum device for holding a central portion of the blank defined by at least two of said transverse score lines in contact with said moving means throughout movement of the blank along its predetermined path during folding, said vacuum device comprising a pair of elongated suction boxes disposed adjacent and parallel to the said moving means, each of said suction boxes having an open grid-like cover and a perforated endless belt partially supported by said cover and mounted for continuous longitudinal movement with respect to said cover, a pair of air folding rails positioned along the path of said moving blank, each of said air folding rails being formed from tubing and connected to a source of compressed air, a plurality of perforations in each of said air folding rails extending along the length thereof and positioned at predetermined radial positions with respect to the longitudinal axis of said rail and arranged to deliver a plurality of jets of compressed air continuously against the blank as it is moved through said apparatus whereby outer portions of said blank along said transverse score lines are brought into face-to-face engagement with the central portion of the blank, said jets of compressed air having sufficient force to prevent contact of the blank with said air folding rail during said folding. 